


Call of the Forest

by Silverashchaos



Category: Undertale (Video Game)
Genre: Eventual Smut, F/M, How Do I Tag, Mating Cycles/In Heat, Multi, Non-Traditional Alpha/Beta/Omega Dynamics, Reader Is Not Chara (Undertale), Reader Is Not Frisk (Undertale), Reader is a mage, Reader is a survivor, Reader-Insert, Reverse Harem, Skeletons, Skeletons are kinda like fea in this, Undertale Skeletons in Heat, Undertale aus, destined mates, i guess?, more tags to come, new Undertale Au?, no beta reader we die like men
Language: English
Status: In-Progress
Published: 2020-11-29
Updated: 2021-02-12
Packaged: 2021-03-10 02:48:05
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 6
Words: 4,384
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27737128
Author URL: https://archiveofourown.org/users/Silverashchaos/pseuds/Silverashchaos
Summary: Those who hear and know of the serine call of the forest know better than to wonder into the forest alone. For if you do follow its cursed song, then you will never truly be able to return to the life you once had.Once you hear it, you can never unhear it.Once you see what the song hides, you can never be hidden yourself.Once it enters your SOUL you will never be free of its call.
Relationships: Axe (horrortalesans)/Reader, Black (swapfellsans)/Reader, Red (underfellsans)/Reader, Sans (Undertale)/Reader
Comments: 18
Kudos: 209





	1. It Calls

**Author's Note:**

  * Inspired by [The Soldier and the Carnal Skeletons](https://archiveofourown.org/works/18068075) by [Writers_War_Z0ne](https://archiveofourown.org/users/Writers_War_Z0ne/pseuds/Writers_War_Z0ne). 



The sound of your own footsteps on the pebbled beach was the first thing you heard. Your vision also returning, although its still blurry, it was hard to focus on anything. Your body still moving along the waters edge.

The sound of the crashing waves and the calls of seagulls came next, your feet still moving, carrying your numbed body along.

You don’t remember getting up and walking. What you do remember is the screaming of the other passengers, and the overwhelming fear as the....

As the....

Your legs buckle, sending your knees crashing into the pebbles, the ringing in your ears returning as it began to take over. Your arms hanged limply at your sides before becoming tense as your hands balled into fists.

As the plane began to fall....

A sound bubbles out from your raw throat, a cry, a shout, a scream.... A roar.

You let it all out.

The pain, the fear, the desperation, the dread, the anger.....the excitement. It all came out.

Not again.....

You don’t want to do this again.....

When you could no longer scream out, you fell silent and sound returns once more.

The numbing feeling begins to disappear, the cuts and burns on your arms and legs were making themselves known now. Your clothes are soaked from the ocean water and the wind on the beach was making your body shiver from the cold.

Your vision finally began to clear up. Turning your head to the right, you only saw the ocean and the waves crashing into large rocks in the not so far off distance. Turning to the left, your gaze was met with trees, massive pine trees and a lonesome mountain off in the distance.

Why did this have to happen again?

You can feel it calling out to your SOUL.

Before you knew it, you were standing and your feet were carrying you towards the trees. Which at this point you noticed that you only have one shoe. Tendrils of purple magic trail behind you and spark across your skin. Your inventory opens, your hand lifts slowly and before you could stop yourself, you select the one thing that you never thought you would use again.

The weight on your head and shoulders brings an odd mix of comfort and dread. The thick black fur that rests on your shoulders and back brings warmth to your cold and sore body. The skull that rests upon your head brings a sense of protection. The skull that belonged to a bear once, was much larger than your own head to the point that you are able to look through the eye sockets of the skull. The lower jaw hangs loosely, and was only kept in place by leather strips that was attached to the skull itself.

Your SOUL….

It’s welcoming the siren call of the wild.

You can’t resist the it anymore.

Another item is selected from your inventory before your magic dismisses it. The spear of bone and wood brings a sense of power. The weapon was over six feet tall, and the spear head was made of bone that came from the same bear.

You don’t look back to the beach and the crashing waves as you disappear into the massive forest.


	2. The First Song

**Summary for the Chapter:**

> We take a look into the past

_“Mummy?.... Daddy?”_

_“Mummy?! Daddy?!” Tears being to fill your eyes as you called out for your parents again and again. Your little legs carrying you around the rubble of the plane and the strangers that laid there on the ground._

_Why was no one moving? You don’t understand._

_“M-mummy?” No matter how long you walked around the plane, you couldn’t find your parents. Your small hands rub at your dirt and tear covered face as you plunk yourself onto the ground. Sniffling you pull your backpack off of your back and look through it._

_Your purple blankie and teddy was the first things you saw. Slowly you pull them out and hug both items to your face, another sniffle escaping you. Placing your blankie and bear down, you look into your backpack again. There sat a bottle of water and a few snacks that mummy packed you, and daddy’s book. Reaching in you pull out the book that you loved so much. It was old and you couldn’t read the front anymore but you knew what it said anyways. After all, you and daddy read the book many times before bed time!_

_Looking up from the book, you looked around at the tall trees that surrounded the plane. Your eyes would fall back to the book before you slowly opened it and began to flip through the pages, finding comfort in it. You continued to flip through the pages until you came across a image of a plane._

_“P… Plaaane cr-.. Crassshh.. Plane crash… and what to do… A-after” You slowly spoke, making sure to say each word right. You looked at the image of the plane, broken and surrounded by trees, before looking around yourself once again. You felt tears starting to form in your eyes once again._

_Mummy said that planes never crash… But this one did._

_You can’t find mummy or daddy._

_You don’t want to be all alone._

_But you can hear something, a song, as you look at the trees._

_With a small whimper you put the book back into your backpack along with your teddy and blankie. Getting up from the ground you start to walk around, you were tried._

_Maybe you can find a spot to curl up and sleep in?_

_It took some time but you end up finding a couple of seats under the wing of the plane. Climbing up onto the seats before pulling your backpack off and pulling out your teddy and blankie. You end up using your backpack as a pillow as you curl up on the seat. You cuddle your teddy as your blankie helps bring you some comfort and warmth._

_You stare out at the trees, listening to the song as sleep slowly takes over._


	3. Odd Human

**Summary for the Chapter:**

> oh look we got a skele

**Notes for the Chapter:**

> heads up anything after - - - - - signals a POV change

Huffing through your nose, you get up from the creek side you had been resting at and move to follow it up stream. It took what you assumed was several hours of walking through the pine forest to find any fresh flowing water. A much needed resource for you to live in the forest. Nearly the entire time it felt like someone or something was watching you. It was doubtful that it was another survivor of the plane crash, they would have stayed there at the crash site. 

So that meant it was either an animal, which was also unlikely because it would have attacked by now. Or something else entirely different, which you hoped it really wasn’t anything like things from before. Your grip on your spear tightens and loosens out of habit at the thought of facing those dark creatures again. 

Either way you were sure to keep your guard up as you kept a eye out for a suitable place to make your home. Some where that was close enough to water but not so close that it will get flooded come spring. 

Your purple eyes drift from place to place as your bare feet carried you through the trees. You had long sense ditched your remaining shoe. Admittedly you were no longer used to walking in a thick forest without shoes, no matter it won’t take long for your feet to harden once more. 

Your would come to a stop as you steeped out into a large clearing, your violet eyes widening as you took in the massive oak in the centre of the field of golden grass. The late afternoon sun only adding to the glow of the meadow. The tree itself looked to be well over 200 feet tall and some of the lower branches looked to be nearly two feet wide. The golden grass in the meadow came up to your waist.

As the wind blew towards you from the oak, your eyes closed as you took a deep breath of the fresh air. The pain in your SOUL finally, finally felt like it was starting to lift. Your head tilts to the side slightly as you hear a song once more. 

A song so similar to the one you heard all those years ago.

\- - - - - - - - - - 

For hours now Black had been following the strange female human. Black couldn’t make heads or tails of the female and her actions, she wondered off from the rest of her kind without looking back or any concern for their safety! It made him wonder if she even knew if there were others. Not to mention the display of magic, the skull mask and the spear she has is something to worry about. 

It didn’t matter for the others, the youngest was sure to get the humans on the beach. 

But this female? He had to keep following her.

When the female came across the creek, Black was sure she would stop and attempt to make a camp there like any other human. But nooo, the female just had to keep walking, following the creek and heading straight for the neutral grounds. Black just didn’t understand what she was looking for and he wasn’t sure if he should stop her before she got onto neutral land or not. 

Sure letting her wondered into the others territories would mean he didn’t have to deal with the human but that also would mean he would get an ear full later on if she went into the Red’s land. Even Sans was bound to cause trouble for him if Black let her wonder over there as well.

Black would pause in the trees as he saw the human stop and stare at the massive oak tree in the field. Confusion would quickly take over Black as he watched the human seem to relax.

It… It looked like she could hear it.

But that wasn’t possible.

The human was fully grown. How could she hear it?

Unless…. 

No that couldn’t be it….. Right?


	4. Mother Tree

**Summary for the Chapter:**

> Thats one big tree

**Notes for the Chapter:**

> So i know its been a little while sense i posted last and im sorry about that! But i would like to say THANK YOU to everyone who has read and left kudos! I never thought that something that i wrote would get over 700 hits and 80 kudos! Thank you again everyone!

Sans had been taking a nap in the old Mother Tree when he felt it. Black’s magic and the magic of another he didn’t recognize. Sitting up Sans’ white eye lights flicked over to a human standing on the edge of the meadow. HIs eyesights narrow before flicking over to where Black was hiding in the trees not too far away from the human.

Sure Sans had saw the human plane crashing into the beach, but he thought nothing of it. Axe was sure to pick off the survivors as per usual. But for a human to not only wonder away from the crash and have magic, they made their way to the neutral grounds and to the Mother Tree. 

A low rumble would come from Sans before he took ported out of the tree and appeared behind Black. The younger Skeleton would jump at Sans’ appearance, Black whipping around with hidden sockets. Sans would make a shushing motion with his hand before grabbing Black and porting them further away from the human so they could talk. 

As soon as Sans felt solid ground beneath his feet once more, his gaze flicked back to the human. At this distance he can now tell that its a female and she no longer looked relaxed. In fact she was looking at the spot he and Black once was standing before her head slowly turned towards where they were currently standing. 

Sans’s eye lights disappear as he watched the female. 

It shouldn’t haven’t been possible for her to feel his magic.

Both Sans and Black stood there, not daring to make a move or a sound as the human stared them down. They stayed like that for sometime before the human finally returned their violet gaze back to the Mother Tree.

“What In Stars Are You Doing Sans?! She Almost Caught Us!” Black hissed out through his bared teeth.

“you were about to confront the human black. thats not your job” Sans growled back at Black, making the younger Skeleton to shrink back slightly at Sans’ tone. 

In the corner of Sans’ eyes he could see how the human still had their head tilted towards them, listening. 

“That Human Can Hear It Sans”

“what?! that… that’s not possible black. they are an adult!”

“You Don’t Think I Don’t Know That?! That Human Can Hear It And They Have Magic Sans! Not To Mention They Can Feel Our Magic And Made It Here To The Mother Tree!” Black hissed out causing Sans to give out an exasperated sigh as he rubbed his face. 

This was something that the eldest didn’t want to deal with, not now, not ever. But it seems the forest has chosen the human and now all he can do is watch and see if the human passes the trails the forest give them in the coming days.

“fine, fine! I will let the others know, you watch the human and tonight we will meet on my side of the meadow.” Sans huffed out before he ported out to find not only Red but Axe as well. Leaving Black to watch over the human for the time being.

\- - - - - - - - - - - - - -

You give out a small hum as you eyed the old oak tree. Judging by its size and the magic you can feel coming off of it, the tree was more then likely the Mother Tree. You honestly didn’t think you would ever come across another Mother Tree in your life time. The tree, the Mother Tree was the one who birthed the forest and the creatures that are currently watching you. 

If you remember correctly people called them, Fea? 

Fea sounds right. 

You flick your purple gaze to where the Fea are hiding at the moment, you couldn’t see them, they were too far in the trees but you could hear their voices. You couldnt make out their words but you heard them never less. The language barrier was going to be an interesting thing to try and fix, wether you learn their language of they learn yours.

Once more your gaze returns to the Mother Tree, you stand there listening to the song for a few moments longer before you head for the tree. As you do so you hear something that sounds like someone a strangled noise of surprise. 

As you moved you feel the wind slow to a gentle breeze, and once you got to the base of the Mother Tree, the wind had stopped completely. Gently you set your spear onto the ground before pulling the skull up from your face until it was resting on top of your head. Tilting your head back you look up the massive tree in awe, a soft smile appearing on your lips. 

Slowly you return your gaze back to the base of the tree, which is as wide as two full pick up trucks parked side by side. Reaching out, you lay your hand on it’s bark before gently resting your head against it as well. A sigh escapes you as you feel the magic pulsing gently through out the tree.

“I hear your call old one.” You spoke softly as your magic began to thrum in tune with the tree. “I wish to stay here, will you allow me to stay here in your forest?” Your eyes close as you listen to the song once more. Now at the source, you can feel and hear how different this song is from the one you grew up to. 

“Is there a place you will allow me to stay?” Your eyes open as you feel the wind once more, however it wasn’t blowing away or towards you this time. It was blowing up from the ground. You could feel many tiny hands trying to push, to urge you to go up. Pulling away from the tree you look up at the swaying branches before you being to climb up.

As you climbed you felt the tiny hands telling you where to grab and where to move. It wasn’t until you felt like you were half way up the tree before you saw it. The tree suddenly opening up to a massive hallow, it was widen enough for you to comfortably sleep in. You feel the wind change once more, blowing into the hallow and the hands seemed to move in excitement to try and get you to go into the hallow. 

Slowly you climbed into the hallow and found that it was covered in soft moss, leaves and other warm materials. It looked like a nest and it probably once was. The hallow was also warm and comforting, you could feel your body giving into exhaustion. Laying down in the soft material of the nest, you can feel the events of the day catching up with you.

You were tired.

So tired.

As your eyes closed you could make out something peaking into the hallow and watch as sleep claimed your tired mind and body.


	5. One

**Summary for the Chapter:**

> We see who the others are and uh oh whats this?

**Notes for the Chapter:**

> I just want to say thank you to everyone for reading and liking this story! It really means a lot to me.

Black had done as he was told, he watched the human.

Sure he nearly choked on a non existent lung full of air when he saw the human head for the Mother Tree. It shocked him to his SOUL, humans normally become fearful the closer they get to the Mother Tree. But this human, this human wasn’t, she only seemed to be happy the closer she got to it. Black grips the front of his black tunic as he remembers the scene that played out before him. 

His SOUL keeps doing flips at the memory.

“oi! stop spacing out black! ya need to tell us wha’ happened!” Red hissed out at Black in his usual gruff manner.

“black focus. what happened after the human approached the mother tree?” Sans huffed out as he rubbed his skull, his irritation showing.

“Well She Set Her Weapon Aside And Asked Mother Tree If She Could Stay Here In The Forest And If There-“

“what?!” “wha’?!”

“Let Me Finish Talking! She Also Asked If There Was A Place For Her To Stay. The Sprites Came Out And Got Her To Climb The Mother Tree-“

“they did what?!”

“Stars Be Damned! Will You Morons Shut It?!” Black hissed out, getting annoyed with his siblings interrupting him. “As I Was Saying. They Got Her To Climb Up To Our Old Nest, She’s Asleep Up There Now” Black huffed out as his purple eye lights drift back to the Mother Tree. The female looked peaceful as sleep took her, and stars the song her SOUL was singing.

“perfect, this is just perfect!” Sans growled out, his hands being thrown up into the air before the eldest began to pace in front of them. Black rolls his eye lights at the elder’s childish reaction. 

“so wha’ we do now?” Red huffed as his red eye lights glare at the Mother Tree.

“Nothing. The Sprites Have Chosen.” 

“ya well I don’ like it. a human staying in mother tree aint right.” 

“dosent matter if we don’t like it…” Sans grumbled out, looking like he wanted to say more. 

A blast of violent magic washed over Black, snapping him out of his thoughts as his head whipped towards his territory. His eye lights shrinking to pin pricks as he sees Axe lumbering out of the trees and heading for the Mother Tree.

“We Need To Stop-“

“no, we will see how this plays out” Sans interrupted Black with a low growl. The hiss and retort Black had been about to shoot back to Sans quickly died in his throat at the look he received from the eldest. 

A scream ripping through the air causes Black to whip around in time to see the human being thrown out of the Mother Tree.

To Black the sky had never looked so red before as the sun began to set.

Black couldn’t hear the song as the human scrambled to their feet and stare in fear at the youngest of skeletons.

\- - - - - - - - - - - - - 

Air had been knocked out of your lungs when your body had hit the ground even when you had attempted to soften the blow with your magic. It still hurt, but you lucky reacted in time to not end up with a broken bone or two. 

A blast of violent magic caused you to scrambled up to your feet in fear, your purple eyes snapping over to the source of the magic.

Fear was the first thing you felt when you saw the skeleton and felt the magic it was gathering. But the longer you looked at it, a different emotion began to take over. 

Sadness.

You felt sad when you looked at the skeleton. It’s skull was broken, a large hole took up most of its head and one eye light was missing completely. The other eye light seemed to take up most of its socket and was a ruby red in colour. It clothes are torn and bloody. The axe in its hand was so large that it dragged on the ground behind the massive skeleton. 

Even from where you were, you could tell that the damage was bad and it had been caused by a human. 

You can understood why it was angry. After all you are a human and you were sleeping in the Mother Tree. 

If you had to guess, the skeleton was one of the guardians of the forest.

As you move to stand up straight and after a moment of fighting with yourself you dispel your magic. You watch as the skeleton pauses and tilts its head at you in what you assumed to be confusion. You would find your vision drifting back to the skeletons bloated red eye light. 

Only for your hand to grip the front of your dirtied shirt when your eyes met. 

The feeling of your SOUL lurching in your chest nearly took your breath away.

The skeleton's eye light shrinks to the size if a pink prick as its hand shoots up to it's tattered shirt. A look of disbelief quickly comes across it's face as the axe in its hand drops to the ground with a heavy thud. A single broken word leaves it, no, his mouth.

"mmaate"


	6. Fate

**Summary for the Chapter:**

> A flash back of the good ol' times

_“Anna, who was that you were talking to?” You look up at the older women as she turned around to look down at your small form. You often had seen your caretaker talking to someone, even though you couldn’t see them, you could hear the whispers as they talked back to Anna._

_The older woman smiled gently at you before sitting down in-front of you, the many beads in her brown hair clicking against each other._

_“Well Y/N, im talking to my children.” Her voice had always reminded you of your Granny, soft and warm._

_“Your children? How come I can’t see them?” You asked as your head tilted in confusion._

_“Always the curious one aren’t you? Well my dear, you can’t seem them because they belong to the Other World.”_

_“Like the Guardians and the wind?”_

_“Yes just like them.” Anna chuckled out before reaching out and gathering you into her arms and setting you on her lap._

_“Would you like to learn something else Y/N?”_

_“Oh yes please!” Your excitement causes another chuckle to escape from Anna. She gives out a small hum as her hands run through your hair._

_“As you know, the Guardians are born from the Mother Tree and the everyone else is simply drawn to it from the Other World. As great protectors as they are, the Guardians are not without their faults. They live lonely lives as protesters and rulers of the forest they live in. Seeing the others happy with mates and young of their own only adds to the loneliness.”_

_“Thats sad. Why dont they find a mate?” You interrupt as you look up at Anna with a confused looked on your face._

_“Shh little one. The others only see the Guardians as rulers and protecters of the forest, and there is a reason for this. The Guardians powers are too much for a regular other to handle, and they would die. So after sometime, once the Guardians have had a chance to become adults and know the world and their land. The Mother Tree lets out a song, a song that calls out to a very few Humans who are still children. This happens all over the world. Once a Human wonders into the forest and find their way to the tree, one of two things will happen.” Anna pauses as she plucks a leaf out of your hair._

_“ One is where the Guardians feel the need to raise the child as their own before the child is found and taken back to the rest of the Humans. Another is if the Guardians have a mate already but a child still appears, the mate will take care of the child until its time for them to go.”_

_“So what happens to the child once they leave?”_

_“They continue their lives with other Humans. Some forget their time in the forest, others remember. But no matter what, they will always feel a pull to the forest, they still hear a song calling out to them. Eventually once they are all grown up, they will find their way back to the forest and to a different Mother Tree. There they will find the Guardians who are fated to be that humans mate. “_

_“Oh so you are the Guardians mate Anna…. Dose that mean I will meet Guardians who will be my mate? How can they tell, is it by our scent or something else?”_

_“Thats right Y/N. They are able to tell from our SOUL. You see our time here leaves a mark on our SOULS that they are able to see once you make eye contact.” Anna explained as you began to play with her beaded hair and a tired yawn escaping your mouth. You could hear Anna continue on talking about how the mark in our SOULS allows them to use magic and soon you would be able to use magic yourself._

_You felt yourself dozing off as Anna kept talking, soon enough all you could hear was the song lulling you to sleep._

**Author's Note:**

> Hello and welcome!
> 
> Thanks for reading this and i do hope you do enjoy your stay!
> 
> Chapters wont be very long in hopes that i will be able to keep updating this story in a timely manner.
> 
> Do let me know if there are any spelling errors as i have no beta reader for this and sometimes i miss things.
> 
> Comments are always welcome and i would love to hear any ideas or theories people have!


End file.
